submature
/ˌsʌbməˈtʃʊə/ /ˌsʌbməˈtjʊə/ /ˌsʌbməˈtʃɔː/adjective
1Of a person, animal, plant, etc.: that has not yet reached maturity; not fully mature.
2 Physical Geography. Of a landform, erosional process, etc.: that has not yet reached the stage of maturity.
Origin
Late 19th century. From sub- + mature.